Managing documentation with GitHub and Jekyll

In my company, we have an open source project, that is running for some time. It is a chat server written in Erlang Recently, we stumbled on a problem. All of our documentation was on wiki pages on github. MongooseIM team puts great effort to keep it always up to date. But what if someone needed docs for old version of Mongoose?

The solutions seemed to be easy. Lets generate html version of docs for every new git tag!

Current docs used Markdown, so to have better versioning, we moved the docs to the repository. This way, when we update the code, we can update the docs in the same commit. If someone checks out some old tag, he will have matching doc in doc folder. Cool!

Now, the hard part! We would like to generate html docs from markdown ones. Why? They would be easier to read and we have greater control over presentation. We can also show docs for couple of recent version without the need to checkout the repo or switching to tags.

The static page generator choice was a no-brainer. Jekyll is not only easy to set up, generates static html from markdown, but also has native GitHub pages support. We used categories to indicate releases and changed permalinks to use the scheme /:categories/:title/ After prepending dates to file names, our docs automatically became posts. That was easy!

Then, we realised, that not everything is so cool…

1. Links between files were broken. In GitHub Flavoured Markdown, when you specify link [some title]( in file, GitHub searches for the file in the same directory as But html generated by Jekyll has <a href=””>some title</a>, which means, that instead of going from /MongooseIM/1.5/ to /MongooseIM/1.5/, it will go to /MongooseIM/1.5/ It will just append the href to the existing url, which does not make any sense.

We thought about changing the base_url, but it is one for entire page, so we would have problems with different docs versions, which was one of the main points of doing the whole html generation!

The easiest solution, we could think of, was going through all markdown files and changing ( to (../ We simply used sed for that. This looks more like an ugly hack, than a solution, though.

2. Erlang code quite often has code like this: {{atom, Something}, Options}. This is syntax for tuples nested in each other. Jekyll uses Liquid for its templating language and two curly braces are used to print variables. The problem is, we wanted to use unmodified markdown files. We don’t have any variables! We even don’t have the jekyll header with title date and other stuff. We were able to squeeze all that into _config.yml.

This lead us to another hack: we’ve added {% raw %} and {% endraw %} to every file before the generation step.

3. All the titles got capitalised. Instead of mod_mam, we now have Mod_mam. It is problematic, because Erlang is case sensitive, so those titles mean two different things…

We haven’t found easy solution to this problem yet. Lets call it a day, we will think about this tomorrow.

How do you manage documentation for your open source projects? Do you use some other tool? Maybe you know, how to make jekyll generate links in some clever way? Do you know, how to disable Liquid for all posts in category? Where do you configure Jekyll to stop capitalising post titles? If you know one of those things, please post a comment :)


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